工厂的实现
Bean:在计算机英语中，有可重用组件的含义 JavaBean：用Java语言编写的可用组件 JavaBean>实体类 它就是创建我们类对象的配置类 第一点：需要一个配置文件来配置我们的类 配置的类容：唯一标识：会限制类名（key,value） 第二点：通过读取配置文件中的类容：反射创建对象 位置文件xml，properties
单例：单例有线程安全问题 多例：执行效力低
单例
public class BeanFactory {
public static Properties properties
;
public static Map
<String,Object> Beans
;
static {
try {
properties
=new Properties();
InputStream in
=BeanFactory
.class.getClassLoader().getResourceAsStream("bean.properties");
properties
.load(in
);
Beans
=new HashMap<String, Object>();
Enumeration
<Object> key
=properties
.keys();
while (key
.hasMoreElements()){
String keys
= key
.nextElement().toString();
String BeanPath
= properties
.getProperty(keys
);
Object value
= Class
.forName(BeanPath
).newInstance();
Beans
.put(keys
,value
);
}
} catch (IOException e
) {
e
.printStackTrace();
} catch (ClassNotFoundException e
) {
e
.printStackTrace();
} catch (IllegalAccessException e
) {
e
.printStackTrace();
} catch (InstantiationException e
) {
e
.printStackTrace();
}
}
public static Object
getBean(String BeanName
){
return Beans
.get(BeanName
);
}
多例
public class BeanFactory {
public static Properties properties
;
static {
try {
properties
=new Properties();
InputStream in
=BeanFactory
.class.getClassLoader().getResourceAsStream("bean.properties");
properties
.load(in
);
} catch (IOException e
) {
e
.printStackTrace();
} catch (ClassNotFoundException e
) {
e
.printStackTrace();
} catch (IllegalAccessException e
) {
e
.printStackTrace();
} catch (InstantiationException e
) {
e
.printStackTrace();
}
}
public static Object
getBean(String BeanName
){
Object Bean
=null
;
try {
String BeanPath
=properties
.getProperty(BeanName
);
Bean
=Class
.forName(BeanPath
).newInstance();
} catch (InstantiationException e
) {
e
.printStackTrace();
} catch (IllegalAccessException e
) {
e
.printStackTrace();
} catch (ClassNotFoundException e
) {
e
.printStackTrace();
}
return Bean
;
}
}
